Problem: If $3a + 9b + 8c = 6$ and $x + y = -6$, what is $-6x + 24c + 27b + 9a - 6y$ ?
Explanation: $= 9a + 27b + 24c - 6x - 6y$ $= (3) \cdot (3a + 9b + 8c) + (-6) \cdot (x + y)$ $= (3) \cdot (6) + (-6) \cdot (-6)$ $= 18 + 36$ $= 54$